NED Abstract

Copyright by European Southern Observatory (ESO).
Reproduced by permission
2016A&A...591A.136L
The far-infrared emitting region in local galaxies and QSOs: Size and
scaling relations
Lutz, D.; Berta, S.; Contursi, A.; Forster Schreiber, N. M.; Genzel, R.;
Gracia-Carpio, J.; Herrera-Camus, R.; Netzer, H.; Sturm, E.; Tacconi, L.
J.; Tadaki, K.; Veilleux, S.
Abstract. We use Herschel 70 to 160 micron images to study the size of
the far-infrared emitting region in about 400 local galaxies and quasar
(QSO) hosts. The sample includes normal "main-sequence" star-forming
galaxies, as well as infrared luminous galaxies and Palomar-Green QSOs,
with different levels and structures of star formation. Assuming Gaussian
spatial distribution of the far-infrared (FIR) emission, the excellent
stability of the Herschel point spread function (PSF) enables us to
measure sizes well below the PSF width, by subtracting widths in
quadrature. We derive scalings of FIR size and surface brightness of local
galaxies with FIR luminosity, with distance from the star-forming
main-sequence, and with FIR color. Luminosities L_FIR_~ 10^11^ L_sun_
can be reached with a variety of structures spanning 2 dex in size.
Ultraluminous L_FIR_>~ 10^12^ L_sun_ galaxies far above the
main-sequence inevitably have small R_e,70_~ 0.5 kpc FIR emitting regions
with large surface brightness, and can be close to optically thick in the
FIR on average over these regions. Compared to these local relations,
first ALMA sizes for the dust emission regions in high redshift galaxies,
measured at somewhat longer rest wavelengths, suggest larger sizes at the
same IR luminosity. We report a remarkably tight relation with 0.15 dex
scatter between FIR surface brightness and the ratio of [Cii] 158 micron
emission and FIR emission - the so-called [Cii]-deficit is more tightly
linked to surface brightness than to FIR luminosity or FIR color. Among 33
z <= 0.1 PG QSOs with typical L_FIR_/L_Bol,AGN_ ~ 0.1, 19 have a measured
70 micron half light radius, with median R_e,70_ = 1.1 kpc. This is
consistent with the FIR size for galaxies with similar L_FIR_ but lacking
a QSO, in accordance with a scenario where the rest FIR emission of these
types of QSOs is, in most cases, due to host star formation.
Key words: Galaxy: structure, galaxies: starburst, galaxies: active